This enables compatibility with versions of git-annex currently
available on GitHub's "ubuntu-latest" image, aka Ubuntu 22.04 Jammy.
Currently, Jammy is shipping git-annex 8.20210223-2ubuntu2.
https://packages.ubuntu.com/jammy/git-annex
Issue #7625
This commit adds a new subcommand named "gitannex", aka
"git-annex-remote-rclone-builtin" when invoked via a symlink.
This accomplishes milestone 1 from issue #7625: "minimal support for the
external special remote protocol".
Issue #7625